public function testHeaderBag()
 {
     $header = new HeaderBag();
     $header->set(new ContentTypeHeader('text/html'));
     $header->set((new CacheControlHeader())->setNoCache());
     $this->assertTrue($header->has('Content-Type'));
     $this->assertSame(2, $header->count());
     $header->remove('Content-Type');
     $this->assertSame(1, $header->count());
 }